Circuit breaker



Oct. 24, 1933.

.1. SLEPIAN CIRCUIT BREAKER Filed April 29, 1927 2 Sheets-Sheet 1 Fly.1.

INVENTOR Joseph Slepian I WITNESSES: RQZMM ATT'ORNEY 2 Sheets-Sheet 2INVENTOR" Joseph Slepmn ATTbR EY J. SLEPIAN cmcuxw BREAKER Oct; 24,1933.

Filed April 29, 1927 I I 1 l/ 1 r WITNESSES:

Patented Oct. 24, 1933 "'PArEur OFFICE.

CIRCUIT Joseph Slep Westinghouse El mum ectrlc &

Pa, to mnhcturlnlconpany, a corporation of I Application April :9, 1m.Serial No. 187,451 11 Claims. (cl. zoo-144) My invention relates tocircuit breakers, and

particularly to are extinguishing devices therefor. One object or myinvention is to provide means for interrupting the flow of electricitythrough gaseous media. Another objector my invention is to provide acircuit breaker provided with an arc-interrupting device capable ofopening highvoltage large current arcs in air or .in gases, withoutrecourse to oil or other arc-quenching media. Some or the aspects of myinvention are, however, applicable in connection with devices foropening circuits of lower power and to a variety of other uses.

The principal field for immediate application of my invention is inconnection with alternatingcurrent circuit breakers and I shall,therefore, describe an embodiment of my invention as applied to suchcircuit breakers, without in any way intending to restrict the scope ormy invention, except as indicated in the appended claims. According tomy invention,.the arc incident to the opening or a circuit is driveninto a deionizing structure comprising a series of spaced metallicplates having tapering notches aligned to form a v-shaped groove. whenforced into the apex of this groove, there is a large deionizing action,and the arc is extinguished as the current passes through zero.

Ey thus rapidly eliminating the ionisation that would otherwise maintainthe electrical conductivity or the path until the line voltage had risensumciently to reignite the arc, current now through the circuit breakeris eflectivelyptopped.

Other objects of my invention will become apparent upon reading therollowing specification.

, In general, my invention comprises the features or construction,combination of elements, and arrangement of parts which will beexemplified in the construction hereinafter set forth and the scope ofthe application of which will be indicated in the claims.

For a more complete understanding of the nature and objects of myinvention, reference should be had to the following detailed descriptiontaken in connection with theaccompam drawings, in which,

Fig. 1 .is a general race view or a contaotor adapted for controllingcircuits comprising three line conductors and which embodies myinvention. Fig. 2 is a sectional view of the main arcing contacts andthe deionizing chamber associated with one supply line or contactor,-

Fig. 3 is a rear view of the deionizing chamber, Fig. 4 is a top view ofthe deionizing chamber,

and,

Pig. Sisasectionalvlewonflaelinesindicated by V-V in Fig. 2.

Referring to the drawing my contactor comprises a base 1 ofinsulating-material ries stationary members 2 or each pair or principalcontact members, the members 2 being bolted directly tothebaee 1.Eachstationarymembcr 2 is provided with a suitable terminal stud 3 towhich supply line connections may be made in the ordinary manner or theart. 05

lhe contacts 2 have a peculiar structure which will be more fullydescribed in connection with the blowout magnets associated therewith.The movable member 4' or eachpair of contacts is a supported on the freeend or a contact support 5, the other end of which is fixed to a crossbar on trunnions 'I slotted recess 9 near the end or the member 5 and,when the contactor is open, is loosely held in place by a stud l0. Stud10 passes through a hole in the contact support 5 and also passes, witha loose ht, through another hole near one end or the 2, when the breakerby flexible leads 13, the stationary are attached to suitable studs 14,15 and 16 tired in the base member 1. connection of the loadlineconductorsmaybe madedirectlytothestuds 14, 15 and 16, if desired.Alternatively, overload relays or known type may bemadeconnectedtoanydtheeestuds;antitdesired,someoithesereiaysmaybemoimtedontheticnedtobeattractedbyamagneticcorelewhu the latter is excited by currentsupplied to the solenoid l9'asaconsequence otcloeumotanauxillery controlcircuit 20 appertaining thereto.'lhiseontrolcircuitmayderlveenergylromany convenient eourcarorexampIeJr-om twoorthe llneterminaletudsaandmaymcludemeerlee no of aninch thick and they ,Iachstatio'nary contactor 2 thebase but their .of areentrant notch toward the upper end of the shape.

housing 21, these V-shaped notches aline to'formof relay contacts bywhich it may be desired to control the opening and closing of thiscontact. Such relays are well-known in the art and constitute no part ofthis invention.

When the solenoid 19 is energized by completion of the control circuit,the lever arm 17 is attracted towardthe core 18; the cross bar 8 isturned on its trunnion 7 and thereby moves contact members 4 into aement with contact members 2, thus closing the line circuits. The leverarm 17 is so disposed relative to the trunv nions supporting the crossbar 6 that the weight of the lever arm 1'! tends to soturn the cross bar6 as to move contacts 4 backward and away from contacts 2. Uponinterruption of the control-circuit 20 the weight of lever arm 1! thusseparates contacts 2 and 4 thereby opening the contactor.

The foregoing describes the general structure of my contactor and itsoperating mechanism. In what immediately follows the deionizingstructure which constitutes a principal feature of my invention will bedescribed.

Each pair of contacts 2 and 4 is supported in a chamber 21 shown indetail in Figs. 2 to 5, inclusive. These chambers have side walls 22 andend walls 23 of a refractory insulating material; but are open at thetop and botom. This chamber 21 is hereafter referred to as thedeionizing chamber, and when the contacts 2 and 4 open, the re-. sultingarc is drawn within the lower. half of chamber 21. Fig; 2 shows chamber21 in the upright position it will have when the contactor ,ls installedon an ordinary switchboard, and the words upper" and lower" herein referto such tion.

In the upper half of the chamber 21 are positioned a series of verticalmetal plates 24, the

configuration of each of which is indicated by Fig. These plates may beof copp r about may be spaced about 5 of an inch apart between theiradjacent faces. They are fixed inthe walls of the chamber 21 by thesmall projections 25 fitting in corresponding socketsinthose walls. Thisseries of plates extends across the entire opening in the upper end morefully appear hereinafter.

is formed in what roughly described as a U-shape and as is in- Fig. 2.The arm of the U farthesti'rom the base'plate 1 extends into the chamber21 in close 'proxlmity'to the innermost member of the .series of metalplates 24.

The end wall of the chamber 21 farther from Fig. 2 The contour oi' theupper end of plates 24 is with sides curving together to a rounded apexabout-two-thirds of the way plate.

Figs. 3 and 5' show the generaloutlines of this notchwhich may beroughly described as of V- Whenthe plates 24 are mounted in the aV-shapedgroove into which the driven to aid in m e quenching it. x

. the arc concentrates in a lower edge is in the form The chamber 21 isheld snugly embraced between the arms of aniron plate 27 of U-shape, thechamber 21 being, in reality, made up of two symmetrical halves ofinsulating material held together bythe pressure of the arms of themembers 2'1 between whichthey are pushed with a friction fit. This isshown more plainly in Figs. 4 and 5, while P18. 2 shows the shape of theside plates constituting the arms of the u which have their upper edgesnear the level of the apex of the V-shaped groove above mentioned, andtheir lower edges slightly above the bottom of the arcing chamber. Thisiron plate member 2'! acts as a blowout magnet for the are drawn betweencontacts 2 and 4, since a magnetic field is set up transverse to thedeionizing chamber in consequence of the magneto-motive force due tocurrent flowing in the arcing contacts 2 and 4, as will be explainedmore fully below.

The deionizingchamber 21 is held in position relative to the contacts 2and 4 by a clip 28 which is adapted to slip with a spring fit over thecontact member 2, as will be apparent from an inspection of Fig. 2.

As has been mentioned, formed. in substantially a U-shape. One arm 29 ofthe U is afiixed tothe base plate 1 by stud 4 while the other arm 30 ofthe U stands inclined *ata slight angle to the face of the base plate 1,

but spaced away from it. The U-shaped iron. plate 27 thus loops aroundthe arm 30 of contact member 2; arm 30 may be termed an arcing horn.Similarly the end 31 of contact member 4 is bent to substantially aright angle andmembers. 2 and contact member 2 is 4 are so positioned ontheir supports. that when the contactor is closed, contact is madebetween them at the lower end of their are horns 30 and 31. Fig. 2illustrates this construction.

In consequence of the above-described arrangement, when the contactoropens under load the movement of the contact member 3 away from thecontact member 2 draws an are between the lower ends of their respectivearc horns 30 and 31. The fiow of this current in the arm 30 of member 2exerts a magneto-motive force to set 0 up in the iron plate-27 a fluxwhich crosses the deionizing chamber 21 in a direction perpendicular tothe path of the are being drawn between the contact members 2 and 4.This magnetic field reacts. in accordance with well-knownelectromagnetic lawsv to drive the arc upward 'in the chamber 21 towardthe plates 24 and into the V-shaped groove formed by the contours oftheir lower ends. The proximity of these relatively cold metal platestends to diminish the cross-sectional area of the are, probably by rapidI extraction of energy in the form of heat and the discharging of ionspresent in the peripheral layers of the arc. At any rate, it is a factthat smaller volume and its voltage-gradient rises. This causes thecurrent to fall to zero more rapidly than it otherwise would. Forcurrents at nearly 100% power factor, the current will reach 'zero whenthe generated voltage is less than the voltage required to maintain thearc in the groove. Then the current will stay zero until the generatedvoltage following its normal sine wave rises to a value again suincientto maintain an arc in'the groove. This, -however, takes so long a timethat during its course the conductivity of the air in the groove iscompletely lost, and the arc does not reignite. If, however, the powerfactor of the current is nearly zero when the current reaches zero thevoltage across the switch rises almost immediately 150 tions, if theplates by .a winding in series would still be-within are between theplates after the current layer on the surface plays to the peak value ofthe generated voltage, which tends to reignite the arc in the oppositesense. The time for this voltage rise depends on the inductance andcapacity of the leads and apparatus to which the switch is connected andis usually of the order of m second. Because this time is so short, itis necessarythat the ions be removed from the arc. with great rapidityif.

reignition is to beprev'nted. The very close proximity of all parts ofthe arc in the slot to the metal plates causes a very rapiddeionization, because all the ions which reach the plates are therebydischarged. The narrower the. slot in which the arc finds itself at thetime of current zero, the more rapid will be the deionization, and

the higher the voltage which may be interrupted at zero power factorwithout arc reignition.

. Under normal operating conditions the strength'of the magnetic fieldof magnet 2"l is of such magnitude in relation to the current andassemblage of plates as to force the arc stream up to the apex of thegroove but not onto the plates 24., and consequentlyits extinctionoccurs within the confines of the groove.

If, however, the magnetic field is made too strong, the arc willbedrivendnto. the spaces between the metal plates 24, and .caused toform a series of short arcs, each short arc having terminals on pairs ofplates 24. Under these condiarc...terminals, the arcs must be moved veryrapidly along the plates 24, and a m etic field sufliciently strong toaccomplish this should be provided, and also the plates 24 shouldbesufiiciently long so that, in spite of the high velocity, the arcs donot reach the end of the structure before the current zero.

In general, however, it may be preferable to work with the magneticfield and structure so proportioned that the arc does not pass beyondthe slot up tothe time it is extinguished.

It will be evident that although in structure described the current inthe arc-horns and arc in constitutes the principal ma net -m forceexciting the blowout magnet, this arrangement is adJunctive rather thanessential to my invention and that excitation of the blowoutmagnet withthe arc or otherwise the scope of my invention. It will be evident that,if the groove, been characterised as V-shaped in my deionizlng structureisto have the effects described. it is advantageous, if not positively Ashallruntoratheranarrowgroovelnorderthat thearcshall be inintimate-contact around a large part of its peripherywith the deionizingplates. 1

- In reference tox-the design of'my deionizing structure, it may heldthat reformation of the 9 3 effectively prevented in" which the are usthrough zero-will be most if the part of the groove located atcurrentzero is sometime to bring the arc'into this narrow slot i'rompoint where it is drawn, it is necessary that the sides of the Vshalltaper in gradually inthe manner showninl igasandd.

A study bf heat flow insuch plates as membars as has shown that only arelatively thin much part in carrying away heat where arcs areextinguishedin half a cycle of cycle current. Hence, the use ofheavydeionizing plates is uneconomical. 'The Y deionizing effect is greaterthe gr eaterthe num- 24 are not to be burned bythe which'has man, thatit very narrow. At the ber of plates; wide spacing is, of course, pooreconomy; and much closer spacing than of an inch would be liable tocause trouble from dust accumulations or accidental introduction ofother foreign matter between the plates. Thus the factors determiningthe design of rm; deionizing structure are evident.

By means of my invention, therefore, the arc incident to opening of intoa deioni'zing structure where it is quenched before its has time toperceptibly burn or pit the plates thereof, this movement along the archorns from its place of initial formation taking place so rapidly thatno appreciable burnin of the contact-members occurs. In consequence,where the prior art has found oil switches necessary, air-break circuitbreakers may be designedaccording to the principles of my invention formany conditions of service, with a re sulting decrease of cost and agreater ease, of installation and the elimination of fire hazard. Evenon services where air-breaks have previ ously been used the circuitbreakers may be made with lighter' parts and are of increased durability.

It will be understood that many features which I have described areadJunctiveto each other.

the contactor is driven.

purposes than those of circuit interruption. I,

therefore, desire that the language of the appended claims shall beaccorded the broadest reasonable construction and that my invention belimited solely by what is explicitly stated in the claims and by theprior art.

I claim as my invention:

i. In combination, means to establish. an arc and a structure comprisinga plurality of conducting plates having open spaces therebetween andalined notches oi V-shape, said notches halving in width in everylongitudinal'distance o from. one tenth inch to two inches andpositioned in a portion of the arc path.

2. In combination, means to establish an are means for moving saidarcinto a deionizing structure,-means for extracting energy from said areas it is being moved into said'structure, said energy-extracting meanscomprising a groove, formed by aligned notches in aplurality ofconducting plates having open spaces therebetweenfsaid notches' being'soammonia increases as 5 increases, lbeing distance measured along theaxis of the notch from its apex and w being width of the notch measuredperpendicular to the axis. 1

3. In combination, means to establish an arc, means for moving said areinto a deionlzing structure; means in intimate contact with said are forextracting energy therefrom a's it is being moved into said structure,said energy-exsaid notches curves convex.

w B r Ef crcee-eectionp! the arc and increase it: current density andpotential.

an: which approaches lero width near its inner en l0.Incombinatiommeanetoeetabliehan arc.meanaiormovinzsaidarcintoadeicniaing means for extracting enemy fromaaidarcasitiabeingmovedintosaidetructme, said enemy-extracting meanscomprising a movetormedbyalignednotcheeinaplurality of conducting plateshaving open spaces there.-

between, me notches being an mm um 1' increaaee'ulincreaeee,'lbein'diatancem uredalongtheaxieotthenotchiromiteapex andicbeingwidth oi thenotch measured perpendiculartotheaxia,and-said openepacea be-' tween theplates extending to two diiierent aidesoithedeionizingetmctureeoaetoprovide through ventilating pae'eageebetween theplates.

11. In an arc-extinguishing device, a plurality of metal plates havingopen spaces therebetween, each of said plates having a notch thereinwhich tapers inwardly, which is large at its entrance and whichapproaches mm width near-it: inner end. and said "open spaces betweenthe plates

